A commercial photographic processing laboratory requires the capability of making vast numbers of photographic prints from equally large numbers of photographic negatives. These photographic negatives are typically handled in long roll form, and are processed in photographic printers by mounting the long roll of negative film on mechanized film drives. Such commercial photographic printers may operate in both automated and semi-automated environments.
Most film drives for use with these photographic printers are either electrically or pneumatically powered. A continuous roll of exposed and developed photographic film is mounted on the feed spool of the film drive and routed across the optical stage of a photographic printer. Individual negative frames are sequentially positioned at the optical stage of the photographic printer by operation of the drive components of the film drive so that one or more photographic prints can be made from each frame under either operator or machine control. Finally, the film is collected on a film take-up spool associated with the film drive.
Because photographic film is manufactured in a variety of different widths, a film drive needs to be capable of variably positioning the film in relation to the photographic printer. The longitudinal centerline of various types of photographic film can then be positioned to correspond with the optical center of the photographic printer.
A number of devices have been developed and utilized, with limited success, to provide the capacity for variably positioning the film in relation to the printer. In my patent application Ser. No. 359,852, filed May 31, 1989, I disclosed an apparatus consisting essentially of two nested brackets, one affixed to the printer work surface, and the second slidably affixed to the first. An alternate type, currently used in printers manufactured by Lucht Engineering, of Minneapolis, Minn., permits the entire drive assembly to slide longitudinally across a limited portion of the printer work station top surface. Both of these devices utilize electronic position sensing switches to relocate the film centerline which has not been entirely satisfactory as it requires sophisticated Hall effect magnetic sensor technology to function with the degree of reliability necessary in a commercial setting. Additionally, removal of the aforedescribed drive mechanisms is frequently time consuming and labor intensive. The present invention addresses these problems.